The then 15-year-old celebrated her first big success when she became the Italian combined champion in 1980. In the same year she won the bronze medal in the downhill at the 1980 European Junior Championships . The next year she was second in slalom at the 1981 European Junior Championships . At the Junior World Championships in 1982 Magoni achieved placements among the top nine in slalom, giant slalom and downhill, thus securing victory in the combined ranking. A month earlier she took part in the World Championships in Schladming , but only achieved 29th place in the downhill. In the World Cup she was among the top ten for the first time on December 10, 1982, the best result of the season was sixth place in Piancavallo on December 17, 1982. She was able to repeat this result on January 23, 1984 in Limone Piemonte .
Magoni achieved the greatest success of her career completely unexpectedly at the 1984 Winter Olympics in Sarajevo : The 19-year-old won the gold medal in the slalom ahead of the French Perrine Pelen and Ursula Konzett from Liechtenstein. On January 14, 1985 the Italian celebrated her only World Cup victory in the Pfronten slalom. A month later she won the bronze medal in slalom at the 1985 World Championships in Bormio . At the 1987 World Championships in Crans-Montana she only finished 24th in giant slalom, in slalom she was already out in the first round. At the 1988 Winter Olympics in Calgary , she reached seventh place in slalom, a little later she ended her career.